Handbook of Plastics, Elastomers and Composites Part 19 doc

In the U.S.A., the recycling rate for HDPE milk and water bottles reached 31.4percent in 1998, for a total of 440 million pounds.. Other HDPE containers were recycled ata rate of 12.3 pe

Recycling Foundation This process begins with color separation, followed by shreddingthe whole bottles, usually in two steps with initial shredding, followed by a finer granula-tion step Next, the shredded material is sent through an air classifier to blow off the lightparticles, which consist primarily of fines and label fragments The material is thenwashed in hot detergent to remove product residues and soften and remove adhesive.Washing is followed by screening and rinsing Next, a density-based separation using hy-drocyclones separates the heavier-than-water PET from the lighter-than-water polyolefins,which consist predominantly of polypropylene from caps and, to a lesser extent, from la-bels The PET is dried and then sent through a metal removal process, often using an elec-trostatic separator.

The Rutgers process was originally developed to handle beverage bottles at a time whennearly all bottles had paper labels, HDPE base cups, and aluminum closures The disap-pearance of the base cups and change from aluminum to PP closures has greatly facilitatedthe recycling process Aluminum, in particular, was difficult to remove and caused seriousperformance problems in the recycled material Metal caps are still used on a few PET con-tainers, but nearly all now use plastic caps and lids A remaining source of aluminum in re-cycled PET is fragments of inner seal materials containing a foil layer, which are sealed tothe container during the packaging process and may not be removed completely when theconsumer opens the container Voluntary design guidelines discourage the use of aluminuminner seals that are not readily removed when the container is opened, but not all manufac-turers adhere to these guidelines.48 Change of the labels from paper to plastic has also fa-cilitated recycling In current processes, the PP label fragments that are not removed duringprevious process steps will be removed with the PP caps in the hydrocyclone

12.3.4 Recycling of Non-bottle PET

While most PET recycling processes in the U.S.A handle only bottles, facilities in many handle mixed PET packaging, including bottles, tubs, dishes, and film, from yellowbag or bin collection of plastics through the Duales System Deutschland (DSD) MostPET recycling in Germany has utilized feedstock recycling (see Sec 12.2.6), but the plan

Ger-is to significantly increase mechanical recycling beginning in 2001.49

PET x-ray film represents another source of recycled material Since these materialsgenerally are coated with silver, there has long been a potent economic incentive for theirrecovery, and silver from x-ray film has been recovered since the early 1900s.50 In suchprocesses, recovered PET can be obtained as a by-product of silver recovery Its recycling

is complicated by the fact that it is generally coated with PVDC Gemark is reported tohave a proprietary process to remove the PVDC.51 In the U.S.A., one recycler of x-rayfilm is United Resource Recovery Corp (URRC) of Spartanburg, SC.52

DuPont operated a feedstock recycling facility, using its “Petretec” process to recoverPET materials such as x-ray film, from 1995 to 1998 but discontinued the operation due topoor market conditions.53

12.3.5 Feedstock Recycling of PET

Recovered PET can be chemically broken down into small molecular species, purified,and then repolymerized The two major processes for tertiary recycling of PET are glycol-ysis and methanolysis Both result in PET that is essentially chemically identical to virginresin and has been approved by the U.S Food and Drug Administration for food contactapplications However, PET produced by these processes is more costly than virgin resin,which significantly limits its use

In 1991, Goodyear obtained a letter of no objection from the U.S FDA for the use of its

“Repete” tertiary recycled PET in food contact applications The process, later sold to

Shell Chemical Co., used glycolysis to partially break down PET, followed by purificationand repolymerization In tests using model contaminants, the contaminants were removeddown to a 50- to 100-ppm level That same year, both Eastman Chemical Co and Hoechst-Celanese Corp received letters of no objection from FDA for their methanolysis-basedPET depolymerization processes.54 Eastman’s “Superclean” process reportedly can han-dle PET bottles of any color, and including multilayer bottles such as those containing ox-ygen barriers, producing new PET equivalent to virgin.55 Methanolysis processes providefull depolymerization and can remove colorants and certain impurities that cannot be re-moved by glycolysis.

Petrecycle Pty Ltd., of Melbourne, Australia, announced in February 2001 that it wouldinstall a chemical recycling system capable of processing more than 22 million pounds ofpost-consumer PET a year in the M&G Finanziaria Industriale SpA virgin PET productionfacility in Point Pleasant, WV Petrecycle’s “Renew” technology will enable M&G to pro-duce a blend of virgin and recycled PET, reportedly for lower costs than those associatedwith other recycling technologies.56

Other tertiary recycling processes include a Freeman Chemical Corporation process toconvert PET bottles and film to aromatic polyols used for manufacture of urethane andisocyanurates.54 Glycolized PET, preferably from film, since it is often lower in cost thanbottles, can be reacted with unsaturated dibasic acids or anhydrides to form unsaturatedpolyesters These can then be used in applications such as glass-fiber-reinforced bathtubs,shower stalls, and boat hulls United States companies that have been involved includeAshland Chemical, Alpha Corporation, Ruco Polymer Corporation, and Plexmar.51 Unsat-urated polyesters have also been used in polymer concrete, where the very fast cure timesfacilitate repair of concrete structures Basing polymer concrete materials, for repair orprecast applications, on recycled PET reportedly leads to 5 to 10 percent cost savings andcomparable properties to polymer concrete based on virgin materials However, they arestill approximately 10 times the cost of portland cement concrete.57

12.3.6 Food-Grade Mechanically Recycled PET

A variety of processes have received official non-objection from the U.S FDA for use ofmechanically recycled PET in food packaging The earliest processes relied on insensitiveuses or on imposition of a physical barrier between the food and the recycled plastic Forexample, the first approval was in 1989 for use of recycled PET in egg cartons.51 Continen-tal PET Technologies received approval in 1993 for a coinjected multilayer PET bottle with

a 1-mil (0.001-in) layer of virgin PET between the core layer of recycled PET and the tainer contents The approach was used initially for soft drink bottles in Australia, NewZealand, and Switzerland.58–60 In 1994 and 1995, Wellman, Inc., obtained approval for use

con-of mechanically recycled PET in multilayer packaging for a variety con-of food products.61The first U.S approval for use of mechanically recycled PET in direct contact with foodcame in 1994, for Johnson Controls’ Supercycle recycled PET In 2000, 6 of the 20 operat-ing PET recycling plants used technologies that have received letters of non-objectionfrom FDA for direct contact with foods and beverages.35 These processes rely on intensivecleaning, often in combination with control over the source material, and have been vali-dated by challenge with known amounts of model contaminants

In 1999, Phoenix Technologies LP became the first company to receive FDA approvalfor use of 100 percent curbside recycled PET in food containers In 2001, the companygained approval for use of this material in hot-filled bottles Commercial production offood-grade curbside recycled PET began in December, 2000 The process is in use in Aus-tralia to make 25 percent recycled-content bottles for Coca-Cola.62

United Resource Recovery Corporation (URRC) of Spartanburg, SC, became the ond U.S company to get approval for food-grade recycled PET from curbside collection

sec-in 2000, for its “Hybrid-UnPET” technology While Phoenix Technologies was expected

to focus on the soft drink market, URRC was targeting the bottled water market, larly in Europe A plant in Frauenfeld, Switzerland, is licensed to use the technology.52The process reportedly involves mechanical recycling without hot water followed by athermal treatment using sodium hydroxide and a final stage for removal of residual con-taminants.63 The treatment with caustic soda results in a solid-phase reaction in which theouter surface of the PET chips is stripped off, and the resulting ethylene glycol and tereph-thalic acid are recovered as by-products Any contamination adhering to the outer surface

particu-is removed during thparticu-is stage Residual contaminants are removed using a combination ofair blowing and controlled temperature The resultant mixture of salt and clean PET gran-ules is separated by mechanical filtration followed by washing and then removal of anysmall metal particles by a metal separator.40 This process, therefore, could be regarded as amix of mechanical and feedstock recycling

Another process producing food-grade recycled PET is the “Stehning BtoB Process,”developed by OHL Apparatebau & Verfahrenstechnik GmbH, of Limburg, Germany,which received U.S FDA approval in 1999 The first production unit began operation inOctober 1999 at PET Kunststoffrecycling GmbH (PKR) in Beselich, Germany Two otherfacilities are also in operation, worldwide, using this technology In this process, the cleanPET bottle flakes, without preliminary drying, are fed into a modified twin screw extruderwhere it is dried and degassed and then melt-filtered and pelletized The amorphous PETchips are fed into a discontinuous solid-stating process for crystallization and condensa-tion/decontamination under vacuum Reportedly, the sensory characteristics of the recy-cled material are superior to those of virgin PET In particular, acetaldehyde and ethyleneglycol levels are lower The German facility has a production capacity of 7,500 tonnes peryear.64

12.3.7 Properties of Recycled PET

Mechanically recycled PET in general retains very favorable properties Some reduction

in intrinsic viscosity is usual, but it can be reversed by solid-stating Residual adhesivesfrom attachment of labels are a common contaminant concern Some of the adhesive resi-due can become trapped in the PET granules and is not removed by washing Since theseadhesives often contain rosin acids and ethylene vinyl acetate, the rosin acids plus aceticacid from ethylene vinyl acetate hydrolysis can catalyze hydrolysis of the PET during pro-cessing A similar problem can be caused by residues of caustic soda or alkaline detergentsfrom the wash step Considerable loss of molecular weight can result, and darkening of theadhesive residues can cause discoloration

PET is very susceptible to damage from PVC contamination, and vice versa nation in the range of 4 to 10 ppm can cause serious adverse effects.65 Because the densi-ties of PET and PVC overlap, density-based separation methods are ineffective.Technologies have been developed for very effective sorting of whole-bottle PVC andPET PVC contamination from materials such as coatings, closure liners, labels, etc., ismore difficult to handle Appropriate package design to avoid the use of PVC or PVDCwith PET containers is the most effective strategy The Association of Post-ConsumerPlastic Recyclers issued a report detailing the effect of PVC contamination of PET, inwhich they estimated that the cost to the domestic PET recycling industry of addressingPVC contamination in 1998 totaled $6.5 million Sorting accounted for 37 percent of thecost, with depreciated equipment, laboratory labor, and maintenance also representing ma-jor costs The average cost was 1.67 cents per pound of PET produced Because costs werelower in larger reclaimers, as well as in those specializing in deposit containers, theweighted average was 0.86 cents per pound.66

Contami-Repolymerized PET is essentially identical in performance to virgin PET

12.3.8 Markets for Recycled PET

One of the earliest large-volume uses for recycled PET was as polyester fiberfill for cations such as ski jackets and sleeping bags The range of applications has grown enor-mously and now includes items as diverse as carpet, automobile distributor caps, producetrays, and soft drink bottles Fiber applications remain the largest market and continue togrow (see Table 12.3) In fact, Aoki International, of Tokyo, introduced an all-recycledmen’s suit made from recycled soft drink bottles The company also promised to recycleused suits returned to their stores into buttons and linings for new suits.67

appli-The first 100 percent recycled PET container in the U.S.A was introduced in 1988 byProctor & Gamble for household cleanser Bottles, including those for food and beverages,are now a significant market for recycled PET, and pressure for bottle-to-bottle recyclingcontinues to grow

Other markets for recycled PET include strapping, sheet, and film A number of performance engineering alloys and compounds utilizing recycled PET have been devel-oped, especially for the automotive industry.51 Recycled PET is being used in manufacture

high-of a drainage filtration mesh for roadways by Viy Plastics, an Australian joint venture.68 AGerman company, Remaplan Anlagenbau BmbH, has developed a plastic pallet madefrom 75 percent post-consumer PET, 20 percent post-consumer polyolefins, and 5 percentadditives It claims the pallets will sell for $10 to $12 each, about the same as wood pal-lets The company can also produce boxes, crates, trays, and similar items.69

As is generally the case for recycled materials, the market situation is strongly affected

by the supply and demand situation for virgin resin When virgin PET supply is low andprices are up, demand for recycled resin is strong During the last half of the 1990s, therewas a significant downturn in recycled PET demand caused by a large increase in produc-tion capacity for virgin resin that drove down price The situation was exacerbated by atemporarily plentiful supply of off-spec resin from new facilities entering production.Some PET recyclers did not survive the lean years Markets recovered somewhat as de-mand grew but have not returned to the 1995 situation where baled PET bottles sold for

$0.27 to $0.35 per pound.70 Prices in 2000 ranged from $0.07 to $0.20 per pound.35

12.4 High-Density Polyethylene Recycling

The sources of high-density polyethylene (HDPE) in the U.S MSW stream are shown inFig 12.21 HDPE is the second most recycled plastic but has been steadily closing the gap

TABLE 12.3 Uses of Recycled PET in the

U.S.A (Millions of Pounds) 35,54

on PET In the U.S.A., the recycling rate for HDPE milk and water bottles reached 31.4percent in 1998, for a total of 440 million pounds Other HDPE containers were recycled at

a rate of 12.3 percent, for an overall bottle and container recycling rate of 19.3 percent Therecycling rate for HDPE packaging as a whole was 10.3 percent The recycling rate forHDPE in durable goods was 8.2 percent, and in nondurables was negligible, for an overallHDPE recycling rate of 8.9 percent.1 While the recycling rates for HDPE are lower than forPET in some cases, the total amount of HDPE recycled exceeds that of PET in all relevantmajor categories: durables, bottles & containers, all packaging, and all MSW (Fig 12.22) The American Plastics Council (APC) reported a 1998 recycling rate for HDPE bottles

of 25.2 percent, for a total of 734 million pounds, higher than the 24.4 percent reported forPET bottles.71 APC reported rates of 24.4 percent in 1996 and 24.7 percent in 1996.71,72Recovery rates for HDPE fell somewhat in 1999, with the rate for natural HDPE bottles(milk and water, primarily) falling to 30 percent from 31 percent in 1998.73

HDPE bottle recycling in the U.S.A is dominated by KW Plastics of Troy, AL, with acapacity of 600 million pounds per year The next largest companies are USPLC, with fa-cilities in Los Angeles, Chicago, and Auburn, MA, for a combined capacity of 125 millionpounds per year, and Clean Tech of Dundee, MI, with 90 million pounds per year.36

12.4.1 Recycling of HDPE Bottles

Unpigmented HDPE milk and water bottles are the most valuable type of HDPE for cling They are made from a high-quality fractional melt index homopolymer HDPE, usu-ally unpigmented, that is suitable, when recycled, for a wide variety of uses Consideringthat these bottles are generally not covered by deposits, their 31.4 percent recycling rate inthe U.S.A in 1998 compared favorably with the 35.4 percent rate for PET soft drink bot-tles.1 Extrusion blow molded HDPE bottles, both pigmented and unpigmented, are ac-cepted for recycling in most community recycling programs Injection blow moldedbottles, which are made from a high-melt-flow HDPE, are undesirable contaminants.Other containers that are unacceptable in many programs include motor oil bottles and

recy-Figure 12.21 Sources of HDPE in U.S municipal solid waste, 1998.1

those that contained caustic cleansers, insecticides, or other materials where product dues could pose a risk.

resi-Ontario, Canada, has had a deposit system for HDPE milk bottles for a number ofyears, charging 25 cents per bottle, which is one of the reasons milk sold in flexiblepouches is popular When the government considered discontinuing the system in 1999,Ontario milk producers, retailers, and packaging suppliers objected.74

The Alberta (Canada) Dairy Council launched a voluntary recycling program in 1999 in

an effort to increase the 35 percent recycling rate for HDPE milk containers to 70 percent.Municipalities and recycling programs receive a payment for collected and densifiedHDPE, subsidized by the Dairy Council, in the form of a guaranteed price of $400 (Cana-dian) per tonne The three Alberta milk processors voluntarily pay two cents for each four-liter milk bottle and one cent for each two-liter bottle into a Container Recovery Fund tosupport the program In its first year of operation, July 1, 1999, to June 30, 2000, the pro-gram collected 1,197 tonnes of material, a 32 percent increase over the previous year,bringing the province-wide recovery rate to 40 percent Sixteen communities and recy-cling authorities achieved recovery rates of 70 percent or more.75

Motor oil bottle recycling is a significant issue, not only because of the volume of tles involved but because of the potential adverse environmental consequences and thevalue of the oil remaining in the bottles Honeywell Federal Manufacturing & Technolo-gies, of Kansas City, has developed a system for recycling motor oil bottles and recoveringboth plastic and oil The system is licensed to ITec International Technologies, Inc., a sub-sidiary of Beechport Capital Inc., which is marketing the systems worldwide ITec esti-mates that about two billion plastic motor oil containers are discarded each year in theU.S.A., each containing, on average, an ounce of oil, for a total of 250 million pounds ofplastic and more than 15 million gallons of motor oil ITec announced in 2001 that it hadreceived an order for two of its systems from OPT Srl in Italy.76

bot-Some programs for used oil recovery also recover oil bottles For example, in Canada,the Alberta Used Oil Management Association (AUOMA) has developed a program for

Figure 12.22 Amounts of recycled HDPE and PET from U.S MSW, by product category,

1998.1

used oil recycling that also includes recycling of oil filters and motor oil containers under

30 liters in size Participating companies pay an Environmental Handling Charge (EHC)

of $0.05 (Canadian) per liter of container size, at the wholesale level The collectors of theused materials receive payment through the program for the returned materials.Saskatchewan and Manitoba are implementing similar programs, and British Columbia isconsidering doing so.77

12.4.2 Recycling of Other HDPE

While most recycled HDPE comes from bottles, limited recycling of other HDPE als also occurs Some recovery of HDPE film occurs along with LDPE when retail bagsare collected for recycling This collection has declined substantially in the last severalyears DuPont operates a recycling program for its Tyvek envelopes As mentioned above,some recycling of HDPE in durable goods also occurs, according to the U.S EPA

materi-12.4.3 Recycling Processes for HDPE

Recycling processes for HDPE bottles are similar to those for PET First, the collectedHDPE is typically sorted to separate the higher-value unpigmented containers In somecases, the pigmented HDPE is further separated into color families Sorting of the unpig-mented bottles is often done prior to initial baling but may be done at a later stage

At the plastics processor, the baled HDPE containers are typically shredded, washed,and sent through either a float-sink tank or a hydrocyclone to separate heavy contami-nants Air classification may be done prior to washing The clean materials are dried andthen usually pelletized in an extruder equipped with a melt filter to remove residual non-plastic contaminants If mixed colors are processed, the result from typical curbside ordrop-off programs is a grayish-green color, which is most often combined with a blackcolor concentrate to produce black products

Several types of contamination are a concern in HDPE recycling The first is nants that add undesired color to natural HDPE A prime culprit is caps on bottles Whileconsumers are generally told to remove caps before turning the bottles in for recycling, asignificant number arrive with the caps still in place, and the caps are generally brightlycolored Most of these are polypropylene, with the next largest fraction polyethylene Nei-ther of these materials are separable in the usual recycling systems, and hence they usuallyremain with the HDPE, where they result in discoloration of the resin Typically, theamounts are low enough that mechanical properties are not affected, but they do impart agrayish color to the material The introduction of pigmented HDPE milk bottles, whichseem to periodically pop up in various places, is a concern to recyclers since, if they werewidely adopted, they could significantly cut into the use of the more valuable natural bot-tles Pigmented HDPE recycled resin typically sells for only 60 percent of the price of nat-ural HDPE.78

contami-A second type of contamination is mixing of high melt flow injection-molding grades

of HDPE with low melt flow blow-molding grades The result can be a resin with diate flow properties that is not desired by either injection or blow molders Since the cod-ing system for plastic bottles (see Sec 12.18) does not differentiate between the two, it isdifficult to convey to consumers in any simple fashion which bottles are desired in the re-cycling system and which are not The recycling process does not separate the two grades,since their densities and most other properties are equivalent Some programs simply ac-cept the resulting contamination, while others try to get the message to consumers, some-times by specifying bottles “with a seam.” Fortunately, the vast majority of HDPE bottles,especially in larger sizes, are extrusion blow molded

interme-Mixing of polypropylene into the HDPE stream is also a concern As discussed above,much of this arises from bottle caps left in place Some also arises from fitments on deter-gent bottles and from inclusion of PP bottles in the recycling stream Since both PP andHDPE are lighter than water, the density-based separation systems commonly employedwill not separate the two resins Fortunately, in most applications, a certain level of PPcontamination can be tolerated However, particularly in the pigmented HDPE stream, lev-els of PP contamination are often high enough to limit the amount of the recycled materialthat can be used, forcing manufacturers to blend the post-consumer materials with otherscrap that is free of PP, or with virgin (often off-grade) HDPE While triboelectric systemsfor separating chipped PP from HDPE are now available, most recycling facilities do nothave such systems.

Finally, contamination of the HDPE with chemical substances that may later migratefrom a container with recycled content to the product can present problems This is a moreserious issue with HDPE than with PET for two primary reasons First, the solubility offoreign substances of many types is greater in HDPE than in PET Thus, the level of con-tamination that may be present is higher Second, the diffusion of most substances is faster

in HDPE than in PET Combined, these factors create a significantly greater potential formigration of possibly hazardous contaminants out of recycled HDPE into container con-tents Nevertheless, use of some types of recycled HDPE for limited food contact applica-tions has been approved by the U.S FDA

The strategies for dealing with potential migration of hazardous substances from cled HDPE are essentially the same as with PET First, a combination of selection of start-ing materials and processing steps can be used to minimize the contamination levels thatare present The first company to obtain a letter of non-objection from FDA for recycledHDPE in direct food contact was Union Carbide, which later sold the technology to Eco-plast, who also received a letter of non-objection.79

recy-Recycled HDPE can also be used in a multilayer structure that provides a layer of virginpolymer as the product contact phase This is the standard approach for laundry products,where FDA approval is not an issue, but where consumer acceptability issues associatedwith objectionable odors in the product surfaced early in the development stage In thiscase, the multilayer bottles used have a layer of virgin polymer on the outside of the bottle

as well as on the inside This not only solved appearance problems that were also ated with the use of recycled plastic, it permitted a significant savings in the amount offairly expensive colorants that are required The middle layer in such structures is com-posed of a blend of recycled HDPE with process regrind An additional benefit from theinner layer of virgin polymer is the better environmental stress crack resistance of the co-polymer virgin HDPE as compared with the regrind/recycle mix

associ-12.4.4 Markets for Recycled HDPE

A major early market for recycled HDPE was agricultural drainage pipe Pipe continues to

be a significant market, but a number of additional markets have developed as well In ticular, coextruded bottles containing an inner layer of recycled HDPE have developedinto a major market Nearly all laundry products sold in plastic bottles in the U.S.A usethis structure, typically incorporating about 25 percent recycled content Motor oil is oftensold in single-layer bottles made from a blend of virgin and recycled HDPE Figure 12.23shows the proportion of recycled HDPE going into various market categories in the U.S.A

par-in 1996

As can be seen, another significant market for recycled HDPE is plastic lumber, 25 cent of total HDPE markets in 1996.2 Use of plastic lumber is increasing, as its benefits oflong life compared to treated wood, freedom from the hazardous chemicals often used inoutdoor grades of lumber, and maintenance of color without painting, are recognized

per-Plastic lumber does carry a higher initial purchase price than wood equivalents, but life cle costing generally shows substantial benefits for plastic Composites of wood fiber andplastic, either HDPE or LDPE, are also growing in use Plastics lumber is discussed inmore detail in Sec 12.18.

cy-Recycled HDPE is also used in manufacture of film, especially for merchandise bags.Often, the material used is recycled milk bottles Recycled milk bottles are being used inmanufacture of milk crates in Australia.80 They are also often used in production of curb-side recycling bins

United States companies that are major users of recycled HDPE include Procter &Gamble, which uses 25 to 100 percent recycled HDPE in most of their household prod-ucts, Clorox, and DowBrands.81 DuPont uses 25 percent recycled HDPE in its Tyvek en-velopes.82 Hancor, which manufactures drainage pipe, was one of the first large-scaleusers of recycled HDPE and continues to be a major user

12.5 Recycling of Low-Density Polyethylene

and Linear Low-Density Polyethylene

Because of the similarity in properties and uses of low-density polyethylene (LDPE) andlinear low-density polyethylene (LLDPE), and because they are often blended in a variety

of applications, use and recycling of LDPE and LLDPE are often reported and carried out

together Therefore, we will use the term LDPE to refer to both LDPE and LLDPE.

Approximately half of the LDPE found in municipal solid waste originates in ing, as shown in Fig 12.24.1 Another sizable fraction comes from nondurable goods, espe-cially trash bags The two main sources of recycled LDPE are both in the bags, sacks, andwraps category: stretch wrap and merchandise bags In contrast to PET and HDPE, curb-side recycling is not a significant factor in recycling of LDPE in the U.S.A Stretch wrap iscollected primarily from establishments such as warehouses and retailers, where largequantities of goods arrive in pallet loads unitized with the wrap Sending such material to

packag-Figure 12.23 Uses of recycled HDPE bottles in the U.S.A., 1996.2

be recycled, rather than paying to dispose of it, often makes economic sense for the panies involved.

com-Recycling of grocery and other merchandise sacks is generally carried out at drop-offlocations At one time, there was a wide network of such sites across the U.S.A., but manymerchants discontinued the program due to contamination and other concerns Bag recy-cling through schools is also available in a significant number of locations

In 1997, New Jersey had a pilot recycling program targeted at nursery and greenhousefilm In the three month project period, it collected nearly 450,000 lb of film, about 45 per-cent of the total used by growers in the state The biggest problem encountered was thedirt in the film The program was successful enough to expand in 1998.83 Chevron oper-ated a pilot project for agricultural film in Vermont in 1997 and 1998.84

Toro Ag Irrigation, based in El Cajon, CA, began a program in 1999 to recycle its Traxx thin-walled drip irrigation hose, made from linear low-density polyethylene Theused irrigation tape could be delivered to Toro dealers and was then sent for recycling.Toro estimated that more than 1 billion feet of drip irrigation tape is sold each year in Cal-ifornia.85

Aqua-The U.S EPA calculated that 120 thousand tons of LDPE/LLDPE bags, sacks, andwraps were recovered in 1998, for a recycling rate of 5.2 percent About 20 thousand tons

of LDPE and LLDPE were recovered from durable goods, a rate of 3.3 percent The all recycling rate for LDPE in MSW was 2.6 percent, up from 1.9 percent in 1997.1

over-In Canada, the Plastic Film Manufacturers Association of Canada and the Environmentand Plastics Institute of Canada (EPIC) have sponsored curbside recycling programs forplastic film of all types By 1996, the program had grown to 146 communities in Ontario

and 19 in the Montreal, Quebec, area In 1998, EPIC published The Best Practices Guide

for the Collection and Handling of Polyethylene Plastic Bags and Film in Municipal Curbside Recycling Programs.86

Processing of film plastics is more difficult than processing of containers The lowerbulk density of the film leads to difficulty in handling the material, and it is more difficult

Figure 12.24 Sources of LDPE/LLDPE in U.S municipal solid waste,

1998 1

to remove contaminants Historically, a large fraction of merchandise bags collected in theU.S.A were shipped to the Far East, where low labor costs permitted hand sorting Stretchwrap is less contaminated, especially if paper labels are not used, and is often handled do-mestically

The Environment and Plastics Industry Council, of Mississauga, Ontario, has devotedconsiderable effort to identifying processing systems capable of handling post-consumerpolyethylene film, as well as to collection of the material, as mentioned above They chose

to focus on dry processing as key to keeping the cost of pelletizing the materials down.EPIC found that pneumatic separation of polyethylene film can remove 98 percent of con-taminants from film that has first been chopped, shredded, or granulated For agglomerat-ing the shredded material, continuous-feed agglomeration was found to be generallysuperior to pellet mill processing and batch-style agglomeration While the equipment wasmore costly than batch agglomeration, labor costs were lower, and product quality washigher.87

A major market for recycled plastic film and bags is manufacture of trash bags, cally in a blend with virgin resin Recycled plastic has also been used in manufacture ofnew bags, bubble wrap, housewares, and other applications A rapidly growing application

typi-is use of recycled LDPE in plastic lumber, as a composite with wood fibers The leadingcompany in this area is Trex Co., of Winchester, VA, which has production facilities in

both Nevada and Virginia The company was cited by Industry Week in 2000 as one of the

most successful small manufacturers in the U.S.19 Boise-Cascade of Boise, Idaho, andLouisiana-Pacific of Portland, Oregon, also manufacture wood/plastic composites fromwood fiber and recovered LDPE, primarily from pallet wrap Trex also recycles contami-nated agricultural film and some material recovered from MRFs.73

12.6 Recycling of Polypropylene

Sources of polypropylene (PP) in MSW in the U.S.A are shown in Fig 12.25 Packagingrepresents 33 percent of the total, and durable goods represent 40 percent There is littlerecycling of PP from packaging, a rate of only 3.2 percent in 1998, nearly all from the

“other plastics packaging” category Most recycled PP comes from durable goods, wherethe recycling rate was 12.4 percent in 1998 A significant amount of this material comesfrom recycling of PP automotive battery cases The overall recycling rate for PP in U.S.MSW in 1998 was 6 percent.1

Lead-acid automotive batteries are prohibited from MSW disposal facilities in 37 U.S.states, primarily due to concern about the effects of lead Several states impose deposits onbatteries Effective recycling programs for these batteries have existed for a number ofyears The Battery Council International reports a 1996 recycling rate of 96.5 percent forlead-acid batteries PP makes up about 7 percent of the battery, by weight, and is recov-ered along with the lead The primary market for the recovered PP is new battery cases Atypical battery contains 60 to 80 percent recycled PP.88

PP spools and wheel counters in disposable cameras are recovered for reuse in grams for recycling these cameras, as will be discussed further in Sec 12.7 Polypropylenehangers from department stores are also sometimes recycled, and some PP is recycledfrom appliances

pro-12.7 Recycling of Polystyrene

Nondurable goods represent by far the largest category of polystyrene (PS) in U.S MSW,

63 percent, with plastic plates and cups alone representing 39 percent (Fig 12.26) ble goods account for about 27 percent, with packaging amounting to about 10 percent.1 A

Dura-substantial amount of PS is used in the building and construction industry, mostly for lation materials, but these wastes are not considered part of the U.S MSW stream.

insu-The EPA reports recovery of about 10 thousand tons of PS from durable goods in 1998,

a recycling rate of only 1.7 percent No significant recovery of nondurable goods was ported Another 10 thousand tons were recovered from the packaging category, for a 4.8percent recycling rate, resulting in an overall recycling rate for polystyrene of only 0.9percent.1

re-Figure 12.25 Sources of PP in U.S municipal solid waste, 1998.1

Figure 12.26 Sources of PS in U.S municipal solid waste, 1998 1

There is very little recycling of food-service PS in the U.S.A In 1989, the NationalPolystyrene Recycling Company (NPRC) was formed by several PS producers, with agoal of achieving a 25 percent recycling rate for food-service PS by 1995 It focused on in-stitutional generators of such wastes, primarily schools, and other cafeterias However, theoperation was plagued by high levels of contamination with food wastes and was unable tooperate profitably Recycling rates and amounts for PS food-service items, including pack-aging, declined after an initial period of growth In 1999, NPRC and its remaining two re-cycling facilities were sold to Elm Packaging Company and its name changed toPolystyrene Recycling Company of America.89 By late 2000, the company evidentlystopped accepting PS food packaging for recycling.90

Nearly all recycling of PS from packaging in the U.S.A now comes from recycling offoam cushioning materials Such recycling has been much more successful than recycling

of food-service PS Recycling rates have, for the most part, been at the 9 to 10 percentlevel for the last several years (Fig 12.27) The American Plastics Council reported a recy-cling rate for EPS packaging of 9.6 percent in 1999, up from 9.5 percent in 1998 Theamount recycled increased by 1 million pounds, reaching 20.2 million pounds in

1999.91,92 The Alliance of Foam Packaging Recyclers reports availability of more than

200 collection sites in the U.S.A and Canada for post-consumer EPS protective ing The organization web site includes information for consumers about collection loca-tions available in their area.91 Much of the collected material is used in manufacture ofnew EPS packaging, often in a blend with virgin resin Cushioning materials made with

packag-100 percent recycled PS are also available

In addition to recycling, there is considerable reuse of expanded polystyrene loose fill.The Plastic Loose Fill Council operates a toll-free “Peanut Hotline” to provide informa-tion to consumers about where to take EPS loose fill for reuse The organization reportsthat over 30 percent of all EPS loose fill is reused, and more than 1,500 collection sites forthe material are available in the U.S.A In addition, post-consumer recycled-content loosefill is widely available.93

One of the leaders in EPS recycling in the U.S.A is FR International, which recycled10.9 million pounds of expanded polystyrene in 2000, an increase of nearly 2 million

Figure 12.27 Recycling of EPS cushioning, U.S.A.91,92

pounds over 1999 The company, which began PS recycling in 1990, now has five cling operations in the U.S.A and also has a UK subsidiary that recycled over 2.5 millionpounds of polystyrene in 2000.94

recy-One of the problems in recycling EPS is the very low bulk density of the material,which makes shipping it over long distances uneconomical International Foam Solutions,Inc (IFS), of Delray, FL, has developed a process that dissolves EPS in a citrus-based sol-vent, producing a gel and eliminating 90 percent of the volume The “Polygel” is stored indrums and shipped to IFS for processing IFS further dilutes the gel, filters out contami-nants, and produces new PS products Contaminant levels are reportedly reduced to lessthan 1 ppm.95 In addition to cushioning materials, the system can successfully recycle PSfrom food service use The company sells or leases its “IFS Solution Machine” to custom-ers and has several food service operations as customers.96 Sony Corporation ResearchCenter, in Yokohama, Japan, has also developed a solvent-based PS recycling system that

uses d-limonene.97

Another company attempting to use food-service PS is Rastra Technologies, Inc Itmanufactures wall panels made of recycled PS and cement In 1999, it participated in a pi-lot with a Florida school district to recycle used PS foam lunch trays In the early 1990s,five McDonalds restaurants were constructed using the company’s insulated concrete form(ICF) panels containing recycled PS hamburger boxes.98

Kodak operates a recycling program for PS in disposable camera bodies, and also cles film containers Recovered camera bodies are ground, mixed with virgin resin, andused in the production of new disposable cameras The PS internal frame and chassis ofthe cameras are recovered intact and reused in new cameras The cameras are collectedfrom photofinishers, who are reimbursed for the cameras they return The company’s pro-gram is active in over 20 countries, and achieves a recycling return rate of over 70 percent

recy-in the U.S.A and approximately 60 percent worldwide Kodak reports that by weight, anaverage of 86 percent of Kodak one-time-use cameras are recycled or reused.99,100

While there appears to be no current commercial use of the system, some years ago, theToyo Dynam company, in Japan, developed a prototype system for feedstock recycling of

PS in which foam PS was ground and sprayed with styrene monomer to dissolve it andseparate it from contaminants The solution was then cracked and vaporized in a heated re-flux vessel.101

Some PS is also recycled from appliances

In Japan, one of the goals of the Japan Expanded Polystyrene Recycling Association(JEPSRA) is to increase recycling of expanded PS The organization reports that 53.6 per-cent of EPS in Japan is used in containers, 32.5 percent in transport packaging, and 13.9percent in building materials and civil engineering applications With a network of morethan 1000 recycling sites, Japan achieved a 35 percent recycling rate for EPS in 2000 (Fig.12.28) JEPSRA has a goal of a 40 percent rate by 2005.102

Korea reports a recycling rate of 48.8 percent for EPS in 1999, excluding building lation and food containers, for a total of 24,371 tonnes The growth in EPS recycling isshown in Fig 12.29.103

insu-The Canadian Polystyrene Recycling Association (CPRA) reports that more than a lion households in Ontario and Manitoba can recycle polystyrene at curbside The CPRArecycling plant in Mississauga, Ontario, has a capacity of up to 3,500 tonnes of PS a year

mil-It accepts both food service PS and cushioning materials.104

Europe also has some recycling of PS food service items as well as cushioning In the

UK, the Expanded Polystyrene Packaging Group (EPS) reports that 4,500 tonnes of panded polystyrene packaging were recycled in 2000, for a recycling rate of nearly 15 per-cent This was a significant increase from the 3,000 tonnes recycled in 1999, a rate of 10percent The growth was attributed to interest in wood replacement products and an in-crease in the price for virgin PS resin as well as efforts by the group to develop recyclingprocesses and raise awareness about the potential benefits of EPS recycling.105

ex-In October 2000, producers of expanded polystyrene from Asia, Europe, and NorthAmerica, representing 28 countries, met in Malaysia to form the International EPS Alli-ance (INEPSA) with a major goal of enhancing EPS recycling.106

Products manufactured from recycled polystyrene include cushioning materials, cultural trays, video and audio cassette housings, rulers and other desktop accessories,clothes hangers, and other items

horti-Figure 12.28 Recycling of EPS, Japan.102

Figure 12.29 Recycling of EPS, Korea.103

12.8 Recycling of Polyvinyl Chloride

Polyvinyl chloride (PVC) in U.S MSW comes mostly from nondurable goods, followedclosely by packaging and durable goods (Fig 12.30) The U.S EPA reports no significantrecycling of PVC from municipal solid waste in the U.S.1 The PVC bottle recycling rate in

1997 was estimated to be only 0.1 percent in 1997, down from 2 percent in 1996 after continuation of a subsidized program by Occidental Chemical Corporation for buyback ofPVC bottles.107 There is limited recycling of PVC from other waste streams, especiallyconstruction and demolition material, which is not classified as MSW Since non-MSWwaste streams account for considerably more PVC and tend to be more uniform thanMSW PVC waste streams, most efforts have focused on these materials

dis-In the U.S.A., the Vinyl dis-Institute publishes a directory of North American companiesinvolved in vinyl recycling, which is also available in searchable on-line form.108 The

2000 edition lists about 270 U.S and Canadian companies, with the type of scrap they cept Nearly 100 are listed as accepting post-consumer materials The directory also listscompanies manufacturing products from recycled PVC A study commissioned by the In-stitute reported that about 18 million pounds of post-consumer PVC were recycled in 1997from sources such as carpet backing, medical products, windows and siding, and packag-ing Recycling of post-industrial materials was a much larger amount, representing about

ac-78 percent of all recycled vinyl Since nearly 70 percent of PVC production goes intoproducts expected to last 10 years or more, recycling of post-consumer materials is ex-pected to be more important in the future.109 The report found that demand for rigid post-consumer vinyl was smaller than the supply, despite the low recovery rates The situationwas somewhat better for flexible materials, but these were valued mostly for their plasti-cizer content, not the PVC itself.110

PVC has been criticized by Greenpeace and also by the Association of PostconsumerPlastic Recyclers, which in 1998 labeled PVC a recycling contaminant, pointing to thefailure of a year-long effort to find markets for recycled PVC and the fact that many oftheir members had to landfill recovered PVC bottles because they could find no marketsfor them.111 After that report, the Vinyl Institute funded a pilot project aimed to jump-start

Figure 12.30 Sources of PVC in U.S municipal solid waste,

1998.1

the PVC recycling market,107 but recycling of PVC bottles in the U.S.A remains tremely rare

ex-In 1999, the National Electronic Distributors Association developed an industry tion paper in which they recommended recycling of PVC tubes used for packaging semi-conductor devices.112 In 2001, a consortium of New Hampshire circuit board assemblersreported success in doing so One company reported saving $1000 per year while divertingover 25,000 lb of integrated circuit chip tubes at just one of the company facilities The re-cycled tubes are made into a variety of products including new circuit chip tubes anddrainage pipe.113

posi-There is some recycling of PVC intravenous bags from hospitals Beth Israel MedicalCenter, in New York City, was one of the pioneers in these efforts.114 Baxter HealthcareCorporation, of Round Lake, IL, participated in a pilot collection program for hospital IVbags Products from the recycled material included floor tiles manufactured by Turtle Plas-tics of Cleveland, OH.109 Conigliaro Industries, of Massachusetts, recycled PVC frommore than 60 hospitals and biotech firms, accepting IV bags, sterile packaging, employee

ID cards, and other medical plastics It also handles roofing membrane, siding, and trial scrap, for a total of 500,000 lb per year.109

indus-A number of projects have focused on recycling of vinyl siding, usually on scrap nating during building construction or remodeling, and often with financial support fromthe Vinyl Institute As a result of one such pilot project in Grand Rapids, MI, recycling of

origi-vinyl siding waste is included in the EPA-funded publication Residential Construction

Waste Management: A Builders’ Field Guide.115 Among the most high-profile pilotprojects are those involving Habitat for Humanity, which builds housing for low-incomefamilies The Vinyl Institute and other PVC-related industry organizations have donatedmoney and materials to some of these projects in addition to supporting recycling effortsfor the PVC scrap generated during construction In 1997, Polymer Reclaim and Ex-change, in Burlington, NC, was recycling about 300,000 lb per month of vinyl siding scrapthrough drop-off sites located at landfills and near manufacturers of mobile and manufac-tured homes.116 A common market for recycled siding is skirting for mobile homes, con-taining between 30 and 100 percent recycled content Other markets include gutters andpipe.109

Other recycling efforts targeted building-related PVC wastes have focused on windowprofiles, carpet backing, and pipe Often, these, along with vinyl siding scrap, are pre-con-sumer rather than post-consumer wastes For example, Mikron Industries, of Kent, WA,and Richmond, KY, buys back its customers’ window scrap and uses the material, alongwith their own process scrap, in new vinyl window extrusions containing 15 to 25 percentrecycled content Excess scrap is used in the manufacture of vinyl fencing, drain channels,and window packaging.109

Several firms recycle PVC wire and cable insulation, primarily from the cations industry The recovered material typically contains small amounts of metal, so it issuitable only for applications that do not require high purity, such as truck mud flaps,flower pots, traffic stops, and reflective bibs for construction workers The source of most

telecommuni-of the material is phone and business equipment wiring that is being replaced by fiber tic cable.117 One such company is Philip Environmental, in Hamilton, Ontario, which re-cycles about 125 million pounds per year of the approximately 500 million pounds of wireand cable scrap generated in North America It purifies the material and resells it for use inproducts such as car floor mats, truck mud flaps, and sound-deadening panels for cars.109Some post-consumer recycled PVC comes from carpet recycling programs, and carpetbacking is also a market for recycled PVC Collins & Aikman Floorcoverings manufac-tures a vinyl carpet backing made of 100 percent recycled PVC While the material can ac-commodate 100 percent post-consumer PVC, lack of supply means current levels are only

op-20 to 25 percent post-consumer, with the remainder being industrial scrap, mostly fromthe manufacture of automotive products.118

There is also considerable interest in recycling of both pre-consumer and sumer automotive scrap, especially in Europe, with legislative requirements for automo-bile recycling For example, in France, the Autovinyle recycling program for PVCautomotive scrap recycled 1,740 tonnes of PVC in its first year of operation, 1997–1998,and reported a goal of 5000 by 2000.119 It appears this goal was not met, since its mostcurrent report is that 2200 tonnes were recycled in 1999 It focuses on plasticized PVCused in dashboard, seat, door panel, and carpet coatings.120

post-con-Delphi Automotive Systems, working with the University of Wuppertal, in Germany,developed a recycling method for PVC insulation on automotive wiring that avoids con-tamination of plastic by wiring by not shredding the wiring Instead, a physical/chemicalprocess including a solvent is used to soften the insulation on the cable so that it falls offthe wires The solvent is removed and the PVC regranulated and used for new cable insu-lation The copper wire is also recovered As of 2000, Delphi was producing approxi-mately 400 metric tons of recycled PVC annually.121

Recycling of post-consumer PVC is more common in Europe than in the U.S.A For ample, the Vinyl Institute estimates that about half of the 4 billion PVC mineral water bot-tles used in France each year are recycled.109

ex-European PVC producers, through the ex-European Council of Vinyl Manufacturers(ECVM), have committed to recycling of PVC The organization has initiated recyclingprograms for products that are easy to identify and separate from the waste stream orwhich can be kept relatively clean, so that a high quality recycled resin can be produced.Products included are bottles, flooring, pipes, roof covering membranes, and window pro-files Target markets for bottles are non-food bottles, pipes, profiles, fittings, sweaters, andshoe soles Flooring, pipes, and window profiles can be recycled into new products of thesame type The target market for roof covering membranes is waterproofing liners Sometake-back recycling programs have also been initiated for blister packs, ID cards, and sta-tionery items Some programs for PVC from cable and leather cloth have been initiated,where markets for these materials, which cannot be separated into pure PVC, have beenidentified Cable is made into industrial flooring, and leather cloth is made into mats andcarpet backing.122

The European PVC Flooring group is investigating mechanical recycling of PVC ing Currently, only about 1,500 tonnes of such materials are recycled each year, due toquality issues The European PVC Window Profiles and related building Products Associ-ation (EPPA) has initiated a project to examine and implement collection and recyclingsystems for PVC window frames.123 VEKA AG has operated a PVC recycling facility inBehringer, Germany, since 1994, which recycles scrap from manufacture of vinyl win-dows, roller blinds, sheet products, and profiles.109

floor-ECVM also proposes recycling of PVC through feedstock recycling processes, rily those treating mixed plastics packaging with up to 10 percent PVC Pretreatment ofthe wastes is required to get halogen content down to the required ppm range Thermal de-halogenation can be used, either in a liquid or fluidized bed hydrolysis, to produce hydro-chloric acid, which is either neutralized or recovered For materials in which the PVCcontent is 30 percent or more, processes need to be designed primarily for the recovery ofhydrochloric acid ECVM reports that there are a number of such processes that have beenproposed, but all are at early stages of development.122

prima-ECVM is funding a pilot plant at Solvay, in Tavaux, France, for feedstock recycling ofPVC The system uses a molten slag bath containing silicates to decompose PVC to hy-drogen chloride, hydrogen, and carbon monoxide The initial feedstock is cable scrap andpackaging, with other potential sources pharmaceutical blister packs, flooring, and cardashboards.121 The products will be used in production of new PVC Capacity of the pilotplant is 2,000 tonnes per year Another feedstock recycling trial is taking place in Schko-pau, Germany, using a rotary kiln incineration process to recover HCl and energy A facil-

ity at Stigsnaes, in Denmark, is investigating recycling of mixed rigid and flexible PVC in

a two-step process involving thermal hydrolysis followed by pyrolysis The aqueous saltsolution produced in the first step will be purified and then discharged into the Baltic Sea.The hydrocarbons, fillers, and heavy metals generated in the second stage will be recov-ered for reuse.123

Solvay is also involved in a consortium building a plant for mechanically recyclingPVC in Ferrara, Italy, that is designed for PVC from cable insulation and packaging Thefacility will use a process, called Vinyloop, in which the PVC is first separated from otherplastics using biodegradable solvents and then filtered and precipitated, and the solvent isrecovered The recycled PVC is reported to be equal in quality to virgin material.125 Thefacility, expected to begin production in November 2001, is designed to handle 10,000tonnes of post-consumer PVC waste per year, mostly composite materials that also containnon-PVC substances.123

IBM reports that, in the UK, it has successfully recycled more than 500,000 lb of PVCsince 1993, using recycled PVC monitor housings to make 100 percent recycled contentcomputer keyboard backs.109

In Japan, the Vinyl Environmental Council, Japan PVC Environmental Affairs Council,and the Plastic Waste Management Institute are involved in developing PVC recyclingtechnologies Many efforts are directed toward removing PVC from mixed plastics frommunicipal solid waste so that the remaining materials can be used in energy generation,such as in blast furnaces and cement kilns, without the problems presented by chlorinecontent There are also efforts to mechanically recycle construction scrap, producing drainpipes and also coextruded window sashes with about 70 percent recycled PVC by weight

in a buried inner layer.126

In fall 2000, Australia announced initiation of nationwide plastic bottle recycling,which is expected to capture more than 20 million PVC bottles per year when fully imple-mented In 2000, recycling rates for PVC bottles were only about 5 percent Recyclingrates for building materials were about 50 percent.127

A variety of products can be made from recycled vinyl Some have already been tioned Re-New Wood, Inc., of Wagoner, OK, uses recycled PVC and wood to make roof-ing shingles that are claimed to be fire, wind, and hail resistant The Eco-Shake shinglesare made from 100 percent recycled post-industrial PVC from manufacture of IV bags,along with sawdust The company claims the shingles themselves can be recycled at theend of their 50-year expected life.128,129

men-Rhoyl, a French clothing manufacturer, is producing sweaters, scarves, and socks from

70 percent recycled PVC mineral water bottles blended with 30 percent wool About 27bottles are needed to produce one sweater.109

12.9 Recycling of Nylon and Carpet

Nylon recycling has been growing rapidly, with most efforts focused on recovery of pet Estimates are that the U.S.A produces 450,000 tonnes per year of nylon 6 carpetwaste, about 25 percent of all waste carpet.130

car-BASF Corp claims to have initiated the first comprehensive recycling program for usedcommercial carpet in the U.S.A and Canada Its 6ix Again program, which began in 1994,provides recycling of BASF nylon 6 carpet manufactured after Feb 1, 1994, and contain-ing 100 percent Zeftron nylon 6 yarn Carpets must not contain halogenated SBR latex;polyester, jute, PVC, or polyurethane backing, nor can it contain arsenic-containing treat-ments, and it must not be contaminated with any hazardous substances Carpets are sent tocollection centers located throughout the U.S.A and Canada BASF recycles the carpetusing chemical depolymerization into caprolactam and repolymerization and uses the ma-terial in new carpet, resulting in closed-loop recycling In 1997, BASF expanded carpet re-